System and method for scheduling in a multi-hop environment

ABSTRACT

In accordance with an embodiment, a method of operating a base station configured to communicate with a relay station includes allocating resources to the relay station. Allocating resources includes receiving feedback data from the relay station and scheduling resources to the relay station based on feedback data. Feedback data includes a total buffer size of the relay station and a number of user devices.

TECHNICAL FIELD

The present invention relates generally to wireless communicationsystems, and more particularly to a system and method for scheduling ina multi-hop environment.

BACKGROUND

Wireless communication systems are widely used to provide voice and dataservices for multiple users using a variety of access terminals such ascellular telephones, laptop computers and various multimedia devices.Such communications systems can encompass local area networks, such asIEEE 801.11 networks, cellular telephone and/or mobile broadbandnetworks. The communication system can use a one or more multiple accesstechniques, such as Frequency Division Multiple Access (FDMA), TimeDivision Multiple Access (TDMA), Code Division Multiple Access (CDMA),Orthogonal Frequency Division Multiple Access (OFDMA), Single CarrierFrequency Division Multiple Access (SC-FDMA) and others. Mobilebroadband networks can conform to a number of system types orpartnerships such as, General Packet Radio Service (GPRS),3rd-Generation standards (3G), Worldwide Interoperability for MicrowaveAccess (WiMAX), Universal Mobile Telecommunications System (UMTS), the3rd Generation Partnership Project (3GPP), Evolution-Data OptimizedEV-DO, or Long Term Evolution (LTE).

Some systems, such as LTE, strive to serve densely populated areas withvery high data rates. One way in which an LTE network can provide densecoverage and high data capacity in a cost effective manner is to utilizeRelay nodes (RNs), which function as base stations to used devices, butdo not have a backhaul connections as base stations do. Instead, the RNcommunicates with an LTE base station (eNB) via a standard LTE radiolink.

One of the functions of the eNB and RN is allocating bandwidth resourcesto user devices. LTE uses OFDMA for physical layer signaling in thedownlink and SC-FDMA in the uplink. Bandwidth in these signaling schemesis shared among multiple users by allocating resource blocks having aportion of spectrum for a certain number of symbol periods. In LTE, theeNB allocates resource blocks to the RN, which, in turn, allocatesresource blocks to user devices in communication with the RN. The eNB,however, does not have full knowledge of the status of individual userdevices in communication with the RN. Rather the eNB relies on feedbackfrom the RN in order to determine how many uplink and downlink resourcesto allocate to the RN.

In some relay systems, the relay communicates with a base station usingflow control techniques. Such flow control techniques include, forexample, signaling the base station to stop sending data whenever therelay node has too much data. Other techniques include, for example, therelay providing the base station with a per-user breakdown of dataresources being used. As more information is sent back to the basestation from the relay, however, system latency increases and a higheramount of bandwidth resources becomes devoted to status signaling.

SUMMARY OF THE INVENTION

In accordance with an embodiment, a method of operating a base stationconfigured to communicate with a relay station includes allocatingresources to the relay station. Allocating resources includes receivingfeedback data from the relay station and scheduling resources to therelay station based on feedback data. Feedback data includes a totalbuffer size of the relay station and a number of user devices.

In accordance with another embodiment, a method of operating a basestation configured to communicate with a relay station includesallocating resources to the relay station. Allocating includes receivingfeedback data from the relay station, the feedback data comprising apercentage of a maximum amount of data, and scheduling resources to therelay station based on the feedback data.

In a further embodiment, a method of operating a relay node configuredto communicate with a base station and user devices includes determiningan amount of buffer space used, determining a number of user deviceswith data, transmitting to the base station feedback comprising thedetermined amount of buffer space used and the number of user deviceswith data, receiving scheduling information from the base station.

In a further embodiment, a method of operating a relay node configuredto communicate with a base station and user devices includes determininga percentage of a maximum amount of data of the user devices,transmitting to the base station feedback comprising the determinedpercentage of the maximum amount of data for the user devices, andreceiving scheduling information from the base station.

In a further embodiment, a relay station is configured to communicatewith a base station and user devices. The relay station includes atransceiver for communicating with user devices and a base station. Therelay station also includes a processor for determining an amount ofdownlink buffer space used, determining a number of user devices withdownlink data, and determining an amount of uplink buffer space present,and a number of user devices that have uplink data. The relay stationfurther includes a transceiver for communicating with user devices and abase station, where the transceiver transmits to the base stationfeedback including the amount of downlink buffer space used, the numberof user devices with downlink data, the amount of uplink buffer spacepresent, and the number of user devices that have uplink data. Thetransceiver for communicating with user devices further receives fromthe base station uplink and downlink scheduling information based on thefeedback.

The foregoing has outlined rather broadly the features of an embodimentof the present invention in order that the detailed description of theinvention that follows may be better understood. Additional features andadvantages of embodiments of the invention will be describedhereinafter, which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiments disclosed may be readily utilized as a basisfor modifying or designing other structures or processes for carryingout the same purposes of the present invention. It should also berealized by those skilled in the art that such equivalent constructionsdo not depart from the spirit and scope of the invention as set forth inthe appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawing, in which:

FIGS. 1 a-1 b illustrate diagrams of an embodiment mobile broadbandsystem;

FIG. 2 illustrates a block diagram showing an embodiment relationshipbetween a base station scheduler and a relay node scheduler;

FIGS. 3 a-3 b illustrate embodiment frame and resource block structures;

FIG. 4 illustrates a block diagram of an embodiment base station;

FIG. 5 illustrates a block diagram of an embodiment relay node; and

FIG. 6 illustrates a block diagram of an embodiment user device.

Corresponding numerals and symbols in the different figures generallyrefer to corresponding parts unless otherwise indicated. The figures aredrawn to clearly illustrate the relevant aspects of the embodiments andare not necessarily drawn to scale.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The making and using of various embodiments are discussed in detailbelow. It should be appreciated, however, that the present inventionprovides many applicable inventive concepts that can be embodied in awide variety of specific contexts. The specific embodiments discussedare merely illustrative of specific ways to make and use the invention,and do not limit the scope of the invention.

The present invention will be described with respect to variousembodiments in a specific context, scheduling transmissions for awireless networks in a multi-hop environment. Embodiments of theinvention may also be applied to transmission in other types ofnetworks.

An illustration of an embodiment mobile broadband system 100 isillustrated in FIG. 1 a. Mobile broadband system 100 has base station102 that communicates with mobile terminals or user equipment (UE) 104,106 and 108. Base station 102 also communicates with RN 110, which is incommunication with UEs 112 and 114. While one base station 102, one RN110 and five UEs 104, 106, 108, 112 and 114 are shown for simplicity ofillustration, multiple cells, RNs and UEs can be used and provided forin real systems.

An illustration of an embodiment multi-hop mobile broadband system 150is illustrated in FIG. 1 a. Mobile broadband system 100 has base station102 that communicates with mobile terminals or user equipment (UE) 104,106 and 108. Base station 102 also communicates with RN 110, whichcommunicates with second RN 120. RN 120 is in communication with UEs 112and 114. This system is a multi-hop system because communication betweenthe base station and UEs 112 and 114 are first relayed to RN 110, andthen relayed to RN 120 before being transmitted to UEs 112 and 114.While one base station 102, two RNs 110 and 120 and five UEs 104, 106,108, 112 and 114 are shown for simplicity of illustration, multiplecells, RNs and UEs can be used and provided for in real systems. Inembodiments, communication between the base station and the UEs can berelayed by any number of RNs. In further embodiments, a RN can serviceone or more downstream RNs as well as UEs.

FIG. 2 illustrates a block diagram illustrating the relationship betweenbase station scheduler 202 and the RN scheduler 204. Base stationscheduler schedules resources for UEs 210, 212, 214 and RN scheduler204. RN scheduler 204 schedules resource for UEs 216, 218 and 220.Feedback link 206 provides feedback from the RN scheduler to the basestation scheduler.

FIG. 3 a illustrates an embodiment frame according to an embodiment LTEtransmission scheme. Each frame lasts 10 ms and contains 20 slots 0 to19 that last about 0.5 ms each. Two slots make up a transmission timeinterface (TTI) lasting about 1 ms. In alternative embodiments, othertechnologies, frame structures and timing can be used.

FIG. 3 b illustrates a downlink LTE resource block according to anembodiment of the present invention. Each LTE resource block is made ofsix or seven OFDM symbols in the time domain and 12 subcarriers in thefrequency domain. Each subcarrier of an OFDM symbol is referred to as aresource element. Each slot, however, can contain multiple resourceblocks. For example, in an embodiment with a 1.4 MHz channel bandwidth,there are 72 occupied subcarriers yielding 6 resource blocks. In anembodiment having a 5 MHz channel bandwidth, there are 300 occupiedsubcarriers yielding 25 resource blocks. Other combinations are possibleaccording to the LTE specification. In alternative embodiments, theresource block can be an arbitrary number of symbols in the time thetime domain using an arbitrary number of subcarriers in the frequencydomain. In further embodiments, other modulation schemes can be usedbesides OFDM, for example, Single Carrier, CDMA, OFDM/OQAM and resourceelements can be other types of symbols besides OFDM symbols, such as asingle carrier frequency division multiple access (SC-FDMA) symbol.

In an embodiment, the base station also schedules uplink transmissions.The uplink scheduler of the base station assigns the RNs and UEs timeand frequency resources as well as modulation and coding rates.Downstream UEs and RNs, on the other hand, determine the content of whatis transmitted to upstream base stations and RNs. In an embodiment, LTEsystem, resources are allocated within SC-FDMA symbols. Alternatively,if other uplink transmission schemes are used,

In am embodiment, the base station scheduler schedules downlinkresources according to the following utility function for the first hopwhen an RN is present:

$\begin{matrix}{{U = {\frac{r}{r_{ave}}\alpha{\sum\limits_{j \in {UE}}\gamma}}},} & (1)\end{matrix}$where the summation is over all UEs served by the RN. In an embodiment,r is a number of bits that can be transmitted using available resources,and r_(ave) is an average rate of a user. In embodiments, a user can bea user device, or another RN. Furthermore, γ is a weighting factortaking into account higher layer priorities, and α, which is between 0and 1, is used for flow control. If the buffer size is too large at theRN, α is reduced so that fewer resources are transmitted and the buffersize is reduced. On the other hand, if the buffer size is too small, αis increased, thereby increasing the amount of resources. In someembodiments, the choice of α is determined using control strategiesknown in the art. For example, in one embodiment, a PID controller isused to determine α. In an embodiment, weighting factor γ is adjusted togive priority to higher priority user devices, for example, user devicesthat are transmitting or receiving guaranteed bit rate (GBR) data.

In other embodiments, other utility functions targeting differentfairness/throughput/delay balances may be used. For example, inembodiments, proportionally fair (PF) schedulers and/or non-PFschedulers can be used, and the usage of the feedback α is modified toreflect the used utility functions. Complexity reduction techniques suchas choosing user first then resources, or limiting the subset of usersfor which the utility is calculated can also be applied as known to oneskilled in the art.

In an embodiment, α is a constant that depends on buffer sizes at theRN. The determined α depends, for example, on the backhaul of the basestation, UE rates, as well as the scheduling algorithm used. In someembodiments, α is updateable as time goes on. In an embodiment, α isdetermined as follows. First, α is initialed to be α₀=1. Next, at everyx time periods, α is updated as follows:

$\begin{matrix}{e_{i} = \left\{ {{\begin{matrix}{\sum\limits_{j \in {UE}}\frac{B_{{actual},j} - B_{{desired},j}}{B_{{desired},j}}} & {{per}\mspace{14mu}{UE}\mspace{14mu}{feedback}} \\\frac{B_{{actual},{RN}} - B_{{desired},{RN}}}{B_{{desired},{RN}}} & {{per}\mspace{14mu}{QoS}\mspace{14mu}{feedback}}\end{matrix}\alpha_{i + 1}} = {{\alpha_{i} - {K_{p}e_{i}} - {K_{i}{\sum\limits_{j = 0}^{i}e_{j}}} - {{K_{d}\left( {e_{i} - e_{i - 1}} \right)}\alpha_{i + 1}}} = {{{\max\left( {0,\alpha_{i + 1}} \right)}\alpha_{i + 1}} = {\min\left( {\alpha_{i + 1},1} \right)}}}} \right.} & (2)\end{matrix}$where K_(p), K_(i), and K_(d) are chosen to achieve fast convergence,B_(actual) is the instantaneous buffer size at the RN, and B_(desired),is the target buffer size based on traffic type and RN capabilities. Inone example, K_(p),=0.01, K_(i),=0.5 and K_(d)=0.005, however, in otherembodiment, other values can be used. In other embodiments otherparameters other than buffer size are targeted such as delay within theRN buffer, dropped packets etc.

In an embodiment, the value of α could be fed back to the base stationfrom the RN or the calculations could be based on buffer status updatessent periodically from the RN to the base station. In alternativeembodiments, α can be determined differently.

In an embodiment, the scheduler calculates the utility function for eachuser per resource block. The resource block is then assigned to a userdevice and/or a resource node based on the calculated utility.

In an embodiment, r_(ave) is generated using a filter. In one embodimentthe following exponential filter is used:

$\begin{matrix}{r_{{ave},i} = \left\{ \begin{matrix}{{r_{{ave},{i - 1}}\left( {1 - W} \right)} + {Wr}_{t}} & {{Buffer} > 0} \\r_{{ave},{i - 1}} & {{else},}\end{matrix} \right.} & (3)\end{matrix}$where r_(t) is the amount of data transmitted in a TTI. If no data istransmitted, then r_(t)=0. Buffer is the number of bits that are stillto be sent in that QoS Class Identifier (QCI), and W is a windowingparameter.

In an embodiment, the RN scheduler feeds back information to the basestation scheduler by transmitting α to the base station. Here the RNtransmits the required α instead of actual buffer size. In oneembodiment, the RN would transmit a quantized message requesting that itreceive a certain percentage of the maximum amount of data, which wouldbe the amount of data received if α=1. In a further embodiment, themaximum amount of data is the amount of data that would be scheduled forthe RN if no flow control was enabled.

In one embodiment, transmitting α includes sending a number between 0and 1, where α represents an absolute fraction of a maximum data. Forexample, 0 represents 0%, 0.5 represents 50% of the maximum data, and 1represents 100% of the maximum data. Alternatively, a relative numbercan be transmitted. For example, the RN could request 10% more data or10% less data. In some embodiments, the base station keeps track of thecombined messages and caps the range of α between 0 and 1. In a furtherembodiment, a combination of sending an absolute fraction and a relativenumber can be used, for example, a message could either be absolute orrelative depending on the message sent or configuration used. In oneexample, message containing α is 3 bits long the first bit indicating ifthis is a relative or absolute change, and the second 2 bits representthe different values for either the absolute or the relative alpha. Forexample, if α is absolute the two bits are mapped to [0 0.33 0.66 1]. Ifα is relative, the two bits map to [0.8 0.9 1 1.1]. In alternativeembodiments, other mapping schemes and mapped values can be used.

In an embodiment, the RN transmits multiple α values, where each α valueis associated with a category associated with the user device. Forexample, these categories can be a category for each UE, a category foreach quality of service (QoS) classification, or a category per UE andper QoS. Quality of service categories can include, for example, thosedefined in IPv6 such as conversational voice, real time gaming etc. Infurther embodiments, grouping can depend on other factors, for example,channel rates, UE speeds, physical location. Groupings can also bedefined arbitrarily.

In an embodiment, UEs allocated to different groups, and downlinkresources are scheduled according to the following utility function:

$\begin{matrix}{{U = {\frac{r}{r_{ave}}{\sum\limits_{j \in {UE}}{\sum\limits_{i \in {GROUP}}\gamma_{j}}}}},} & (4)\end{matrix}$where r is the instantaneous rate of the backhaul, and r_(ave) is theaverage rate of the backhaul, and GROUP represents groups of UEs. UEswhich are not RN would only reflect themselves and the summation wouldonly be of a single point. In a further embodiment, rather than havingthe summation in the utility function, a modified filter function isapplied to r_(ave). In one embodiment, r_(ave) is determined as follows:

$\begin{matrix}{r_{{ave},i} = \left\{ \begin{matrix}{{r_{{ave},{i - 1}}\left( {1 - W} \right)} + {W\frac{r_{t}}{\sum\limits_{j \in {UE}}{\sum\limits_{i \in {GROUP}}\gamma_{j}}}}} & {{{any}\mspace{14mu}{Buffer}} > 0} \\r_{{ave},{i - 1}} & {{else},}\end{matrix} \right.} & (5)\end{matrix}$where the scheduling utility function is:

$\begin{matrix}{U = {\frac{r}{r_{ave}}.}} & (6)\end{matrix}$

In embodiments having delay sensitive traffic, for example, when groupsrepresent different QoS groups, the following utility function is usedfor scheduling:

$\begin{matrix}{{U = {\frac{r}{r_{ave}}\alpha{\sum\limits_{j \in {UE}}{\gamma\;{f_{QoS}(d)}}}}},} & (7)\end{matrix}$where ƒ_(QoS)(d) is a monotonic increasing function, d is a delay timesince a packet has arrived in the queue at the BS dependent on delaythreshold dth of the various QoS categories. The length time a packet isvalid is represented by dth. In one embodiment,

$\begin{matrix}{{f_{QoS}(d)} = {1 + {{\mathbb{e}}^{d - \frac{dth}{2}}.}}} & (8)\end{matrix}$For non-delay sensitive traffic, ƒ_(QoS)(d)=1. In further embodiments,other functions for ƒ_(QoS)(d) can be used. In further embodiments,ƒ_(QoS)( ) can be a function of all the packets in the queue, orprevious elements of the queue and not just the oldest one, forinstance, scheduling methods involving average transmission delay in thequeue.

In embodiments, α transmitted to the base station from the RN is used bythe base station scheduler to schedule downlink resources.Alternatively, this data can be used to schedule uplink resources.

In an embodiment, uplink resources are scheduled also using the utilityfunction:

$\begin{matrix}{U = {\frac{r}{r_{ave}}{\sum\limits_{j \in {UE}}{\gamma.}}}} & (9)\end{matrix}$In an embodiment, the summation is made over the number of UEs that havedata in the RN buffer. In an embodiment, the RN feeds back a totalbuffer size for the RN and the number of user devices serviced by the RNor devices services by the RN that have data present at the RN totransmit to the BS.

In a further embodiment, the RN feeds back a total buffer size and thenumber of user devices serviced by the RN or devices serviced by the RNthat have data for each of a number of different classifications. Insome embodiments, the total buffer size could be broken down into thesegroups as well. For example, these categories can be a category for eachUE, a category for each quality of service (QoS) classification, or acategory per UE and per QoS. Quality of service categories can include,for example, those defined in IPv6 such as conversational voice, realtime gaming etc. In further embodiments, grouping can depend on otherfactors, for example, channel rates, UE speeds, physical location.Groupings can also be defined arbitrarily.

In a further embodiment, the RN feeds back a total buffer size and thenumber of user devices or devices serviced by the RN that have activedata in the RN buffer where the user devices/services have beenpre-divided into different categories using long term signaling. Theseusers can be divided into groups based on their approximate channelqualities or other factors depending on implementation. In someembodiments, the utility function of equation (4) and the exponentialfilter of equation (5) is used.

In a further embodiment, the RN feeds back the total buffer size for apre-divided set as mentioned above, as well as an explicit indication ofwhich UEs have active data in the RN buffer. This explicit indicationcan be in the form of a bitmap, UE id or some other compression method.

In an embodiment, delay sensitive resources are scheduled by the basestation according to the following utility function:

$\begin{matrix}{{U = {\frac{r}{r_{ave}}{f\left( {d/d_{th}} \right)}\gamma}},} & (10)\end{matrix}$wherein U is the utility function, r is a number of bits that can betransmitted using available resources, r_(ave) is an average rate of auser in a particular channel quality index category, γ is a weightingfactor based on the particular channel quality index category, d is adelay time since a packet has arrived in the queue at the BS, d_(th) isa delay threshold representing a length of time a packet is valid, and ƒis a monotonic function. In some embodiments, ƒ is an exponentialfunction such as equation (8).

A block diagram of an embodiment base station 400 is illustrated in FIG.4. Base station 400 has base station processor 404 coupled totransmitter 406 and receiver 408, and network interface 402. Transmitter406 and receiver 408 are coupled to antenna 412 via coupler 410. Basestation processor 404 executes embodiment methods and algorithms. In anembodiment, base station 400 is configured to operate in a LTE networkusing an OFDMA downlink channel divided into multiple subbands and usingsingle carrier FDMA in the uplink. In alternative embodiments, othersystems, network types and transmission schemes can be used, forexample, 1XEV-DO, IEEE 802.11, IEEE 802.15 and IEEE 802.16. Inalternative embodiments, base station 400 can have multipletransmitters, receivers and antennas (not shown) to support MIMOoperation.

A block diagram of an embodiment relay node 500 is shown in FIG. 5.Relay node 500 has donor antenna 520, which transmits to and from thebase station and is coupled to coupler 518, transmitter 522 and receiver516. Service antenna 512, which transmits to and receives signals fromuser devices is coupled to coupler 510, transmitter 506 and receiver508. RN processor 514, which is coupled to both the donor and servicesignal paths, controls the operation of relay node and implementsembodiment algorithms described herein. In an embodiment of the presentinvention, relay node 500 is configured to operate in a LTE networkusing an OFDMA downlink channel divided into multiple subbands and usingsingle carrier FDMA in the uplink. In alternative embodiments, othersystems, network types and transmission schemes can be used.

A block diagram of embodiment user device 600 is illustrated in FIG. 6.User device 600 can be, for example, a cellular telephone or othermobile communication device, such as a computer or network enabledperipheral. Alternatively, user device 600 can be a non-mobile device,such as a desktop computer with wireless network connectivity. Userdevice 600 has mobile processor 604, transmitter 606 and receiver 608,which are coupled to antenna 612 via coupler 610. User interface 602 iscoupled to mobile processor 604 and provides interfaces to loudspeaker614, microphone 616 and display 618, for example. Alternatively, userdevice 600 may have a different configuration with respect to userinterface 602, or user interface 602 may be omitted entirely. Inembodiment, user device is configured to operate according to embodimentalgorithms. In alternative embodiments, user device 600 can havemultiple transmitters, receivers and antennas (not shown) to supportMIMO operation.

In accordance with an embodiment, a method of operating a base stationconfigured to communicate with a relaying station includes allocatingresources to the relay station. Allocating resources includes receivingfeedback data from the relay station and scheduling resources to therelay station based on feedback data. Feedback data includes a totalbuffer size of the relay station and a number of user devices. In anembodiment, the base station is an eNodeB operating on a LTE network,and the relay station is an RN. In an embodiment, the number of userdevices includes a number of user devices for which the relay stationhas data in its buffer. In a further embodiment, the feedback datafurther comprises an identity of the user devices for which the relaystation has data. In an embodiment, scheduling resources includesscheduling resources using a proportionally fair (PF) scheduler. In afurther embodiment, a non-PF scheduler is used.

In a further embodiment, the user devices includes categories of userdevices, and the feedback data further includes a number of user deviceswithin one of at least one of the categories, and a buffer size for atleast one of the categories. In some embodiments the categories comprisequality of service (QoS) categories. In an embodiment the users forwhich the relay has data are indicated using a bitmap.

In one embodiment, scheduling resources includes using a utilityfunction:

${U = {\frac{r}{r_{ave}}{\sum\limits_{j \in {UE}}\gamma}}},$where U is the utility function, r is a number of bits that can betransmitted using available resources, r_(ave) is an average rate of auser, and γ is a weighting factor taking into account higher layerpriorities. In some embodiments, allocating resources includesallocating uplink resources.

In accordance with another embodiment, a method of operating a basestation configured to communicate with a relay station includesallocating resources to the relay station. Allocating includes receivingfeedback data from the repeating station, the feedback data comprising apercentage of a maximum amount of data, and scheduling resources to therelay station based on the feedback data. In an embodiment, thepercentage includes a relative percentage of calculated maximum amountof data. In a further embodiment, user devices includes categories ofuser devices, and the feedback data further includes a percentage of amaximum amount of data for at least one of the categories. In anembodiment, allocating resources includes allocating downlink resources.

In a further embodiment, a method of operating a relay node configuredto communicate with a base station and user devices includes determiningan amount of buffer space used, determining a number of user deviceswith data, transmitting to the base station feedback comprising thedetermined amount of buffer space used and the number of user deviceswith data, receiving scheduling information from the base station. In anembodiment, the method further includes categorizing the user devicesinto categories, and determining a number of user devices in eachcategory. In some embodiments, the feedback data further includes thenumber of user devices in each category.

In an embodiment, the method also includes determining an amount ofbuffer space used for each of the categories, and the feedback datafurther includes the amount of buffer space used for each of thecategories. In some embodiments, the buffer space used includes bufferspace for downlink transmission to the user devices.

In a further embodiment, a method of operating a relay node configuredto communicate with a base station and user devices includes determininga percentage of a maximum amount of data of the user devices,transmitting to the base station feedback comprising the determinedpercentage of the maximum amount of data for the user devices, andreceiving scheduling information from the base station. In anembodiment, the percentage comprises a relative percentage of a previousamount of data.

In an embodiment, the method further includes categorizing the userdevices into categories and determining a percentage of a maximum amountof data of the user devices in each category. In some embodiments, thefeedback further includes the maximum amount of data of user devices ineach category. In a further embodiment, determining the percentage ofthe maximum amount of data includes determining the percentage of themaximum amount of data for a downlink path.

In another embodiment, a base station includes a transceiver forcommunicating with user devices and a relay station, and a processor forallocating resources to the repeating station. The processor receives afirst and second set of feedback data from the relay station. The firstset of feedback data includes a total uplink buffer size of the relaystation and a number of user devices, and the second set of feedbackdata includes a percentage of a maximum amount of downlink data. Theprocessor further schedules uplink resources to the relay station basedon the first set of feedback data, and schedules downlink resources tothe repeating station based on the second set of feedback data. In anembodiment, the base station is an eNodeB operating on a LTE network,and the relay station is an RN.

In a further embodiment, a relay station is configured to communicatewith a base station and user devices. The relay station includes atransceiver for communicating with user devices and a base station. Therelay station also includes a processor for determining an amount ofdownlink buffer space used, determining a number of user devices withdownlink data, and determining an amount of uplink buffer space present,and a number of user devices that have uplink data. The relay stationfurther includes a transceiver for communicating with user devices and abase station, where the transceiver transmits to the base stationfeedback including the amount of downlink buffer space used, the numberof user devices with downlink data, the amount of uplink buffer spacepresent, and the number of user devices that have uplink data. Thetransceiver for communicating with user devices further receives fromthe base station uplink and downlink scheduling information based on thefeedback. In an embodiment, the relay station is an RN operating on aLTE network, and the base station is an eNodeB.

An advantage of embodiments is that high scheduling performance can beachieved without a high overhead for buffer status feedback. Forexample, in some embodiments, explicit feedback of the different RNbuffer sizes is not necessary to be fed back, thereby saving bandwidthand allowing more bandwidth to be devoted to service content.

Although present embodiments and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. For example,many of the features and functions discussed above can be implemented insoftware, hardware, or firmware, or a combination thereof.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present invention, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present invention. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A method of operating a base station configuredto communicate with a relay station, the method comprising: allocatingresources to the relay station, the allocating comprising receivingfeedback data from the relay station, the feedback data comprising atotal buffer size of the relay station and a number of user devices, andscheduling resources to the relay station in accordance with thefeedback data, wherein scheduling the resources comprises using autility function:${U = {\frac{r}{r_{ave}}\underset{j \in {UE}}{\alpha\sum}\gamma_{j}}},$wherein U is the utility function, r is a number of bits that can betransmitted using available resources, r_(ave) is an average rate of auser, JεUE indicates all user devices served by the relay station, α isa value between 0 and 1 determined in accordance with the feedback data,and γ_(j) is a weighting factor for a j^(th) user device served by therelay station taking into account higher layer priorities.
 2. The methodof claim 1, wherein scheduling resources comprises scheduling resourcesusing a proportionally fair (PF) scheduler.
 3. The method of claim 1,wherein: the base station operates on a long term evolution (LTE)network; the base station comprises an eNodeB; and the relay stationcomprises a relay node (RN).
 4. The method of claim 1, wherein thenumber of user devices comprises a number of user devices for which therelay station has data in its buffer.
 5. The method of claim 4, whereinthe feedback data further comprises an identity of the user devices forwhich the relay station has data.
 6. The method of claim 4, wherein: theusers for which the relay has data are indicated using a bitmap.
 7. Themethod of claim 1, wherein: the user devices comprise categories of userdevices; and the feedback data further comprises a number of userdevices within at least one of the categories and a buffer size for atleast one of the categories.
 8. The method of claim 7, wherein thecategories comprise quality of service (QoS) categories.
 9. The methodof claim 1, wherein allocating resources comprises allocating uplinkresources.
 10. A method of operating a base station configured tocommunicate with a relay station, the method comprising: allocatingresources to the relay station, the allocating comprising receivingfeedback data from the relay station, the feedback data comprising apercentage of a maximum amount of data; and scheduling resources to therelay station in accordance with the feedback data wherein schedulingthe resources comprises scheduling the resources using a utilityfunction in accordance with the feedback data, and in accordance with aratio of a number of bits that can be transmitted using availableresources to an average rate of a user.
 11. The method of claim 10,wherein the percentage comprises a relative percentage of a calculatedmaximum amount of data.
 12. The method of claim 10, wherein: userdevices comprise categories of user devices; and the feedback datafurther comprises a percentage of a maximum amount of data for at leastone of the categories.
 13. The method of claim 10, wherein allocatingresources comprises allocating downlink resources.
 14. A method ofoperating a relay node configured to communicate with a base station anduser devices, the method comprising: determining an amount of bufferspace used; determining a number of user devices with data; transmittingfeedback data to the base station, the feedback comprising thedetermined amount of buffer space used and the number user devices withdata; and receiving scheduling information from the base station,wherein the scheduling information comprises allocated resourcesscheduled with a utility function in accordance with the feedback data,and in accordance with a ratio of a number of bits that can betransmitted using available resources to an average rate of a user. 15.The method of claim 14, further comprising; categorizing the userdevices into categories; and determining a number of user devices ineach category, wherein the feedback data further comprises the number ofuser devices in each category.
 16. The method of claim 15, furthercomprising: determining an amount of buffer space used for each of thecategories, and wherein the feedback data further comprises the amountof buffer space used for each of the categories.
 17. The method of claim14, wherein the buffer space used comprises buffer space for downlinktransmission to the user devices.
 18. A method of operating a relay nodeconfigured to communicate with a base station and user devices, themethod comprising: determining a percentage of a maximum amount of dataof the user devices; transmitting feedback to the base station, thefeedback comprising the determined percentage of the maximum amount ofdata for the user devices; and receiving scheduling information from thebase station, wherein the scheduling information comprises allocatedresources scheduled with a utility function in accordance with thefeedback data, and in accordance with a ratio of a number of bits thatcan be transmitted using available resources to an average rate of auser.
 19. The method of claim 18, wherein the percentage comprises arelative percentage of a previous amount of data.
 20. The method ofclaim 18, further comprising categorizing the user devices intocategories; and determining a percentage of a maximum amount of data ofthe user devices in each category, wherein the feedback furthercomprises the maximum amount of data of user devices in each category.21. The method of claim 18, wherein determining the percentage of themaximum amount of data comprises determining the percentage of themaximum amount of data for a downlink path.
 22. A relay stationconfigured to communicate with a base station and user devices, therelay station comprising: a processor configured to: determine an amountof downlink buffer space used, determine a number of user devices withdownlink data, and determine an amount of uplink buffer space present,and a number of user devices that have uplink data; and a transceiverconfigured to communicate with user devices and the base station,wherein the transceiver is further configured to transmit feedback tothe base station, the feedback comprising the amount of downlink bufferspace used, the number of user devices with downlink data, the amount ofuplink buffer space present, and the number of user devices that haveuplink data, and receive uplink and downlink scheduling information fromthe base station in accordance with the feedback, wherein the schedulinginformation comprises allocated resources scheduled with a utilityfunction in accordance with the feedback data, and in accordance with aratio of a number of bits that can be transmitted using availableresources to an average rate of a user.
 23. The relay station of claim22, wherein: the relay station is configured to operate on a long termevolution (LTE) network; the base station comprises an eNodeB; and therelay station comprises a relay node (RN).